The study of meiosis in Drosophila melanogaster centers on the nature of chromosome synapsis. For this purpose new chromosome types are being synthesized. New experimental methods being developed include the production of free duplications of X-chromosomes and autosomal loci, tests of the effects of additions and subtractions of whole chromosomes to gametes, the possible use of compound chromosomes in synthesizing a tretraploid line of Drosophila, and the divisibility of the telomere in producing new chromosome arrangements.